Ctrl key I just switch from Photoshop elements for Adobe Photoshop CC 2017 few days ago, and I am lost with the control for Photoshop 2017 What will be the control Key for? 1. to change the size of the letters on top of the screen 2. to put 2 pictu

I just switch from Photoshop elements for Adobe Photoshop CC 2017 

few days ago, and I am lost with the control for Photoshop 2017

What will be the control Key for?

1. 1. to change the size of the letters on top of the screen
2. 2. to put 2 pictures at the same time on the screen side by side
3. 3. to put one or several pictures on a blank layer for further composition
4. 4. to undo any mistake and redo what is good

Sincerely yours

Luc Lochard